428 Wisconsin Academy of Sciences, Arts, and Letters. 
segment is more than twice as long as broad, its outer margin 
straight, and its inner with two setose convexities. It is termi¬ 
nated with a finger-like process and a smaller spine nearer the 
inner margin. The foot reaches to the end of the first segment 
of the right exopodite. The endopodite is slender, attenuate 
towards the apex, and reaches to about the middle of the second 
segment of the exopodite. 
Length of the female, 1 to 1.1 mm. Length of the male, 
hardly 1 mm. 
Lilljeborg states that the female carries only two eggs. This 
was not true of the Wisconsin individuals, for they commonly 
had as many as six. This was first described from material col¬ 
lected in Greenland, where it is found as far north as Disco 
island. It appears to be very abundant in the southern part of 
Greenland. It was afterwards reported by DeGuerne and' 
Richard from Iceland. (DeG. and R., ? 92.) It is found in 
Newfoundland. It is perhaps the most common of the Diap- 
tomi in the Great Lakes and Lake St. Clair. It occurs in a 
number of lakes in the northern part of the southern peninsula 
of Michigan, hut these are, for the most part, connected rather 
closely with the Great. Lakes. In Wisconsin it is found in the 
following lakes: Birch, Maple, Tomahawk, Stone, Chain o ? 
Lakes, Elkhart, Green and Geneva; all these are of the deeper 
lakes of the state, although there are others, equal in depth to 
some of these, where it is not found. The most southern point 
at which the species has been found is Lake Geneva. To my 
surprise, I did not find it in my collections from the Northwest 
Territory, but all those collections were in very shallow water. 
One would expect to find it all over British America, wherever 
the environment was favorable. I think it probable that it is 
distributed all over North America east of the Rocky mountains 
and north of the latitude of perhaps 43 degrees. 
